Overcharge protection device with uneven terminal pads

ABSTRACT

An overcharge protection device cover assembly for use with a battery cell housing. The battery cell housing has a first terminal and a second terminal, the overcharge protection device cover assembly including a first terminal pad having a first length. The first terminal pad is contactable with the first terminal of the battery cell housing. The assembly also includes a second terminal pad having a second length that is greater than the first length. The second terminal pad is contactable with the second terminal of the battery cell housing. A reversal device of the assembly is deflectable toward the first and second terminal pads. A conductive element of the assembly is positioned between the reversal device and the first and second terminal pads.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/588,581, entitled “OVERCHARGEPROTECTION DEVICE WITH UNEVEN TERMINAL PADS,” filed Nov. 20, 2017, whichis hereby incorporated by reference for all purposes.

BACKGROUND

The present disclosure relates generally to the field of batteries andbattery cells. More specifically, the present disclosure relates tofeatures of a battery cell that may protect a battery cell from thermalrunaway during an overcharge event.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described below. This discussion is believed to be helpful inproviding the reader with background information to facilitate a betterunderstanding of the various aspects of the present disclosure.Accordingly, it should be understood that these statements are to beread in this light, and not as admissions of prior art.

When charging a rechargeable battery cell, the chemical reactions withinthe battery cell may cause an increase in temperature. Some types ofbattery cells, such as those of lithium-ion (Li-ion) batteries, may besusceptible to thermal runaway, in which the temperature increase causedby the charge cycle causes a further increase in temperature. Thermalrunaway can compromise or destroy the battery cell, but also causedamage to the charger and the housing and/or device in which the batterycell is located.

As technology continues to evolve, there is a need to provide improvedpower sources, particularly battery cells and battery modules, for suchsystems that may be powered by or store their energy using batterytechnologies. For example, certain types of battery modules may undergoovercharge testing to determine boundaries and/or limits of the batterymodule and its individual battery cells. Additionally, in certaininstances, for example due to changing environmental conditions or otheroperating conditions, battery cells may be subject to overcharging.Overcharge tests and overcharging may lead to thermal runaway.Therefore, it is recognized that a need exists for devices that mayprevent or block thermal runaway.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

The present disclosure relates to an overcharge protection device coverassembly for use with a battery cell housing, the battery cell housinghaving a first terminal and a second terminal, the overcharge protectiondevice cover assembly comprising: a first terminal pad having a firstlength, the first terminal pad being contactable with the first terminalof the battery cell housing; a second terminal pad having a secondlength that is greater than the first length, the second terminal padbeing contactable with the second terminal of the battery cell housing;a reversal device that is deflectable toward the first and secondterminal pads; and a conductive element between the reversal device andthe first and second terminal pads.

The present disclosure also relates to an overcharge protection devicecover assembly, the overcharge protection device cover assembly having abase plate including a reversal device, the reversal device beingtransitionable between a first configuration and a second configuration;a first terminal pad having a first length; a second terminal pad havinga second length that is greater than the first length; a conductiveelement between the reversal device and the first and second terminalpads; and a spacer plate between the base plate and the first terminalpad. The first terminal pad is a first distance from the base plate whenthe reversal device is in the first configuration and the secondterminal pad is a second distance from the base plate when the reversaldevice is in the first configuration, the first distance being greaterthan the second distance.

The present disclosure also relates to a battery cell having a batterycell housing, the battery cell housing including first terminal and asecond terminal; and an overcharge protection device cover assemblyaffixable to the battery cell housing. The overcharge protection devicecover assembly includes a base plate coupled to the battery cell housingbetween the first and second terminals, the base plate having a reversaldevice that is transitionable between a first configuration and a secondconfiguration; a first terminal pad having a first end portion, a secondend portion opposite the first end portion, and a first length, thefirst end portion of the first terminal pad being in contact with thefirst terminal; a second terminal pad having a first end portion, asecond end portion opposite the first end portion, and a second lengththat is greater than the first length, the first end portion of thesecond terminal pad being in contact with the second terminal. Thebattery cell also includes a conductive element between the reversaldevice and the first and second terminal pads; and a spacer platebetween the base plate and the first terminal pad, the first terminalpad being a first distance from the base plate when the reversal deviceis in the first configuration and the second terminal pad being a seconddistance from the base plate when the reversal device is in the firstconfiguration, the first distance being greater than the seconddistance.

DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a perspective view of a battery cell having an overchargeprotection device cover assembly in accordance with the presentdisclosure;

FIG. 2 is a cross-sectional view of a first embodiment of the overchargeprotection device cover assembly in a normal operating condition inaccordance with the present disclosure;

FIG. 3 is a cross-sectional view of the first embodiment of theovercharge protection device cover assembly in an electrical shortcircuit condition in accordance with the present disclosure;

FIG. 4 is a cross-sectional view of a second embodiment of an overchargeprotection device cover assembly in a normal operating condition inaccordance with the present disclosure; and

FIG. 5 is a cross-sectional view of the second embodiment of theovercharge protection device cover assembly in an electrical shortcircuit condition in accordance with the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Referring now to the drawings, an overcharge protection device coverassembly 10 constructed in accordance with the principles of the presentdisclosure is shown in FIGS. 1-5. The overcharge protection device coverassembly 10 is shown coupled to a battery cell housing 12 in FIG. 1. Theovercharge protection device cover assembly 10 and the battery cellhousing 12 are collectively referred to herein as a battery cell 14. Inone embodiment, the overcharge protection device cover assembly 10includes a base plate 16 configured to be in contact with, adjacent, orcoupled to the battery cell housing 12, a first (or negative) terminalpad 18 in contact with a first (or negative) terminal 20, a second (orpositive) terminal pad 22 in contact with a second (or positive)terminal 24, a reversal device 26 (reversal device 26 is not visible inFIG. 2), and a conductive element 28 between the reversal device 26 andthe first 18 and second 22 terminal pads. In some embodiments theconductive element 28 is in the shape of disk, but other shapes can beused depending in design requirements, e.g., rectangle, square, etc. Insome embodiments, the reversal device 26 is shaped in the form of adisk, but other shapes can be implemented depending on designrequirements. In some embodiments, the reversal device is formed of ametal or polymer that allows the inner portion of the deflection device26 to deflect from a first position to a second position, the secondposition allowing activation of the overcharging protection byelectrically short-circuiting the battery terminals. In one embodiment,the overcharge protection device cover assembly 10 is configured to becoupled to a surface of the battery cell housing 12 between the first 20and second 24 terminals. In one embodiment, the reversal device 26 isintegrated with, defined by, or coupled to the base plate 16, and atleast a portion of the reversal device 26 is deflectable. Further, thereversal device 26 may be composed of a more flexible material or may bethinner than the base plate 16, such that internal pressure within thebattery cell housing 12 is able to deflect the reversal device 26 butnot the base plate 16. The conductive element 28 is movable, at least ina linear direction that is orthogonal to, or at least substantiallyorthogonal to, the base plate 16. However, it will be understood thatthe first terminal pad 18 and first terminal 20 may instead be apositive terminal pad and positive terminal, and the second terminal pad22 and second terminal 24 may instead be a negative terminal pad andnegative terminal. In some embodiments, the overcharge protection devicecover assembly 10 also includes a vent aperture 30 configured to bealigned with a vent (not shown) in the battery cell housing 12 when theovercharge protection device cover assembly 10 is coupled to the batterycell housing 12. In some embodiments, the overcharge protection devicecover assembly 10 also includes an electrolyte aperture 32 to enable theaddition of electrolyte to battery cell within the battery cell housing12.

The overcharge protection device cover assembly 10 includes asymmetricfirst 18 and second 22 terminal pads. In one embodiment, the secondterminal pad 22 has a length L_(SP) that is less than a length L_(FP) ofthe first terminal pad 18 (for example, as shown in FIG. 2).Alternatively, the first terminal pad 18 may have a length L_(FP) thatis less than the length L_(SP) of the second terminal pad 22. Further,the first 18 and second 22 terminal pads are in contact with or coupledto the first 20 and second 24 terminals, respectively. In oneembodiment, the first terminal pad 18 includes a first end portion 34that is in contact with or coupled to the first terminal 20 and a secondend portion 36 opposite the first end portion 34. The second end portion36 is not coupled to any other component of the overcharge protectiondevice cover assembly 10, and is freely movable relative to the baseplate 16 in a linear direction that is crosswise (e.g., orthogonal) tothe base plate 16. Thus, the first end portion 34 of the first terminalpad 18 includes a pivot point 38 at the first terminal 20 about whichthe first terminal pad 18 may move. Likewise, the second terminal pad 22includes a first end portion 40 that is in contact with or coupled tothe second terminal 24 and a second end portion 42 opposite the firstend portion 40. The second end portion 42 is not coupled to any othercomponent of the overcharge protection device cover assembly 10, and isfreely movable relative to the base plate 16 in a linear direction thatis orthogonal to, or at least substantially orthogonal to, the baseplate 16. Thus, the first end portion 40 of the second terminal pad 22includes a pivot point 44 at the second terminal 24 about which thesecond terminal pad 22 may move. As such, the overcharge protectiondevice cover assembly 10 is transitionable from a first configuration(for example, as in a normal operating condition, as shown in FIGS. 2and 4) to a second configuration (for example, as in an electrical shortcircuit condition, as shown in FIGS. 3 and 5). Although the second endportions 36, 42 are disclosed herein as being movable in a lineardirection relative to the base plate 16, it will be understood that thesecond end portions 36, 42 will move about their corresponding pivotpoints in an arc, albeit a small arc.

Referring now to FIGS. 2 and 3, a first embodiment of an overchargeprotection device cover assembly 10 is shown. The reversal device 26 isdeflectable or transitionable between a first (inverted) configurationand a second (everted) configuration, and transition of the reversaldevice 26 between the first and second configurations causes theovercharge protection device cover assembly 10 as a whole to transitionbetween the first and second configurations. In a normal operatingcondition (e.g., before the reversal device 26 is deflected from anincrease in internal pressure within the battery cell), as shown in FIG.3, the first 18 and second 22 terminal pads are uneven in height,although they each lie in a plane that is parallel to, or at leastsubstantially parallel to, the plane in which the base plate 16 lies.The first terminal pad 18 includes a first (or upper) surface 46 and asecond (or lower) surface 48 opposite the first surface 46. Likewise,the second terminal pad 22 includes a first (or upper) surface 50 and asecond (or lower) surface 52 opposite the first surface 50. When theovercharge protection device cover assembly 10 is in a normal operatingcondition (for example, as shown in FIG. 2), the first surface 46 of thefirst terminal pad 18 and the first surface 50 of the second terminalpad 22 are located at different distances from the base plate 16, thereversal device 26, and the conductive element 28. The second surface 48of the first terminal pad 18 and the second surface 52 of the secondterminal pad 22 are also located at different distances from the baseplate 16, the reversal device 26, and the conductive element 28. Forexample, the second surface 48 of the first terminal pad 18 is located afirst distance DFP from the base plate 16 and the second surface 52 ofthe second terminal pad 22 is located a second distance Dsp from thebase plate 16. To accomplish this, the overcharge protection devicecover assembly 10 also includes a spacer plate 54 between the base plate16 and the first terminal pad 18, thereby positioning the first terminalpad 18 at a greater distance from the base plate 16, the reversal device26, and the conductive element 28. In one embodiment, the spacer plate54 lies in a plane that is parallel to, or at least substantiallyparallel to, the base plate 16. The cross-sectional view of FIG. 2 showsthat the first terminal pad 18 and the second terminal pad 22 are notcoplanar when the overcharge protection device cover assembly 10 is inthe normal operating condition.

Further, each terminal pad 18, 22 has a working thickness T. The workingthickness T is the thickness of at least the second end portion 36, 54of each terminal pad 18, 34 proximate the conductive element 28, at thelocation with which the conductive element 28 comes into contact witheach terminal pad 18, 34 when the overcharge protection device coverassembly 10 is in the short condition. In the embodiment shown in FIGS.2 and 3, the working thickness T of each terminal pad 18, 22 is thesame.

In an electrical short circuit condition (that is, after the reversaldevice 26 is deflected from an increase in internal pressure within thebattery cell), as shown in FIG. 3, deflection of the reversal device 26exerts a force against the conductive element 28, moving the conductiveelement 28 toward and into contact with the second surface 48 of thefirst terminal pad 18 and then the second surface 52 of the secondterminal pad 22. As the second terminal pad 22 is located closer to thebase plate 16, the reversal device 26, and the conductive element 28(due to the lack of a spacer plate 54 between the base plate 16 and thesecond terminal pad 22), deflection of the reversal device 26 will causethe conductive element 28 to come into contact with the second surface52 of the second terminal pad 22 before the second surface 48 of thefirst terminal pad 18. Additionally, as the second terminal pad 22 has agreater length L_(SP) than the length L_(FP) of the first terminal pad18, the second terminal pad 22 is more easily pivoted at its pivot point44 and moved linearly until at least a portion of the second end portion42 of the second terminal pad 22 is at the same distance from the baseplate 16 as at least a portion of the second end portion 36 of the firstterminal pad 18 (for example, as shown in FIG. 3). In one embodiment, atleast a portion of the second surface 48 of the first terminal pad 18and at least a portion of the second surface 52 of the second terminalpad 22 are aligned, as they are both in contact with the conductiveelement 28 when the overcharge protection device cover assembly 10 is inthe electrical short circuit condition. In the electrical short circuitcondition, the conductive element 28 is in contact with both the firstterminal pad 18 and the second terminal pad 22, establishing a shortcircuit to prevent the battery cell from overcharging. When theconductive element 28 is in contact with both terminal pads 18, 22, thesecond terminal pad 22 may be pivoted about its pivot point 44, therebycreating an angle between the plane in which the base plate 16 lies andthe plane in which the second terminal pad 22 lies. This angle may bevery small, such as approximately 10° or less in some embodiments.Further, as the second end portion 36 of the first terminal pad 18 andsecond end portion 42 of the second terminal pad 22 are aligned when theovercharge protection device cover assembly 10 is in the electricalshort circuit condition and reversal device 26 is fully deflected(everted), with the conductive element 28 is at the its furthestdistance from the base plate 16, rather than when the overchargeprotection device cover assembly 10 is in the normal operatingcondition, much less precision is required during manufacture andassembly. Further, the configuration of the first 18 and second 22terminal pads ensures the conductive element 28 will reliably contactboth terminal pads 18, 22 to establish a short circuit when overchargeprotection is needed. It will be understood that although FIG. 3 showsthat the terminal pads 18, 22 are not coplanar when the overchargeprotection device cover assembly 10 is in the normal operatingcondition, and that at least a portion of each of the first surfaces 46,50 of the terminal pads 18, 22 are aligned when the overchargeprotection device cover assembly 10 is in the electrical short circuitcondition, the terminal pads 18, 22 may be configured differently thatthat shown, provided the conductive element 28 contacts one of theterminal pads 18, 22 before the other when the reversal device 26deflects to move the conductive element 28 toward the terminal pads 18,22.

Referring now to FIGS. 4 and 5, a second embodiment of an overchargeprotection device cover assembly 10 is shown. The second embodiment ofthe overcharge protection device cover assembly 10 of FIGS. 4 and 5 issimilar to the first embodiment of the overcharge protection devicecover assembly 10 of FIGS. 2 and 3 and, therefore, the same referencesnumbers are used. However, unlike the first embodiment of the overchargeprotection device cover assembly 10, the second embodiment of theovercharge protection device cover assembly 10 includes first 18 andsecond 22 terminal pads with different working thicknesses T_(FP) andTsp at the second end portion 36 of the first terminal pad 18 proximatethe conductive element 28 and at the second end portion 42 of the secondterminal pad 22 proximate the conductive element 28. In one embodiment,the second terminal pad 22 has a working thickness Tsp that is greaterthan the working thickness T_(FP) of the first terminal pad 18.

When the overcharge protection device cover assembly 10 is in the normaloperating condition, the first 18 and second 22 terminal pads are unevenin height. That is, the first surface 46 of the first terminal pad 18and the first surface 50 of the second terminal pad 22 are located atdifferent distances from the base plate 16, the reversal device 26, andthe conductive element 28. The second surface 48 of the first terminalpad 18 and the second surface 52 of the second terminal pad 22 are alsolocated at different distances from the base plate 16, the reversaldevice 26, and the conductive element 28. For example, the secondsurface 48 of the first terminal pad 18 is located a first distanceD_(FP) from the base plate 16 and the second surface 52 of the secondterminal pad 22 is located a second distance Dsp from the base plate 16.To accomplish this, the overcharge protection device cover assembly 10includes s spacer plate 54 between the base plate 16 and the firstterminal pad 18. The cross-sectional view of FIG. 5 shows that the firstterminal pad 18 and the second terminal pad 22 are not coplanar when theovercharge protection device cover assembly 10 is in the normaloperating condition.

In the electrical short circuit condition, as shown in FIG. 5,deflection of the reversal device 26 exerts a force against theconductive element 28, moving the conductive element 28 toward and intocontact with the second surface 48 of the first terminal pad 18 and thesecond surface 52 of the second terminal pad 22. As the second terminalpad 22 is located closer to the base plate 16, the reversal device 26,and the conductive element 28 (due to the lack of a spacer plate 54between the base plate 16 and the second terminal pad 22), deflection ofthe reversal device 26 will case the conductive element 28 to come intocontact with the second surface 52 of the second terminal pad 22 beforethe second surface 48 of the first terminal pad 18. Additionally, as thesecond terminal pad 22 has a greater length L_(SP) than the lengthL_(FP) of the first terminal pad 18, the second terminal pad 22 is moreeasily pivoted at its pivot point 44 and moved linearly until at least aportion of the second end portion 42 of the second terminal pad 22 is atthe same distance from the base plate 16 as at least a portion of thesecond end portion 36 of the first terminal pad 18 (for example, asshown in FIG. 3). In one embodiment, at least a portion of the secondsurface 48 of the first terminal pad 18 and at least a portion of thesecond surface 52 of the second terminal pad 22 are aligned, as they areboth in contact with the conductive element 28 when the overchargeprotection device cover assembly 10 is in the electrical short circuitcondition. In the electrical short circuit condition, the conductiveelement 28 is in contact with both the first terminal pad 18 and thesecond terminal pad 22, establishing a short circuit to prevent thebattery cell from overcharging. When the conductive element 28 is incontact with both terminal pads 30, 34, the second terminal pad 22 maybe pivoted about its pivot point 44. Further, as the second end portion36 of the first terminal pad 18 and second end portion 42 of the secondterminal pad 22 are aligned when the overcharge protection device coverassembly 10 is in the electrical short circuit condition and reversaldevice 26 is fully deflected (everted), with the conductive element 28is at the its furthest distance from the base plate 16, rather than whenthe overcharge protection device cover assembly 10 is in the normaloperating condition, much less precision is required during manufactureand assembly. Further, the configuration of the first 18 and second 22terminal pads ensures the conductive element 28 will reliably contactboth terminal pads 18, 22 to establish a short circuit when overchargeprotection is needed. It will be understood that although FIG. 2 showsthat the terminal pads 18, 22 are not coplanar when the overchargeprotection device cover assembly 10 is in the normal operatingcondition, and that at least a portion of each of the first surfaces 46,50 of the terminal pads 18, 22 are aligned when the overchargeprotection device cover assembly 10 is in the electrical short circuitcondition, the terminal pads 18, 22 may be configured differently thatthat shown, provided the conductive element 28 contacts one of theterminal pads 18, 22 before the other when the reversal device 26deflects to move the conductive element 28 toward the terminal pads 18,22.

An overcharge protection device cover assembly constructed in accordancewith the principles of the present disclosure provides certain benefitsover currently known overcharge protection devices. For example, theovercharge protection device cover assemblies 10 disclosed herein eachinclude terminal pads 18, 22 of unequal heights from the base plate 16and conductive element 28 when the overcharge protection device coverassembly 10 is in a normal operating condition. This reducesmanufacturing cost and complexity, as the terminal pads 18, 22 do notrequire precise alignment during assembly. Further, the terminal pads18, 22 also are of unequal lengths (that is, the second terminal pads 22are longer than the first terminal pads 18) to allow the longer terminalpad 22 to pivot more easily on its pivot point 44. During an electricalshort circuit condition, deflection of the reversal device 26 causes theconductive element 28 to contact the longer second terminal pad 22before the shorter first terminal pad 18. When the reversal device 26 isfully deflected and the conductive element 28 has been moved to itsfarthest position from the base plate 16, the first 18 and second 22terminal pads are aligned. This configuration ensures that theconductive element 28 will reliably contact both the first 18 and second22 terminal pads to establish a short circuit when overcharge protectionis needed. In contrast, prior art overcharge protection devices requireprecisely aligned terminal pads for reliable overcharge protection,which increases manufacturing cost and complexity.

In one embodiment, an overcharge protection device cover assembly 10 foruse with a battery cell housing 12 having first terminal 20 and a secondterminal 24 includes a first terminal pad 18 having a first lengthL_(FP), the first terminal pad 18 being contactable with the firstterminal 20 of the battery cell housing 12, and a second terminal pad 22having a second length L_(SP) that is greater than the first lengthL_(FP), the second terminal pad 22 being contactable with the secondterminal 24 of the battery cell housing 12. The overcharge protectiondevice cover assembly 10 also includes a reversal device 26 that isdeflectable toward the first 18 and second 22 terminal pads and aconductive element 28 between the reversal device 26 and the first 18and second 22 terminal pads.

In one aspect of the embodiment, the first terminal pad 18 includes afirst end portion 34 and a second end portion 36 opposite the first endportion 34 and the second terminal pad 22 includes a first end portion40 and a second end portion 42 opposite the first end portion 40, thefirst end portion 40 of the first terminal pad 18 being contactable withthe first terminal 20 of the battery cell housing 12 and the first endportion 40 of the second terminal pad 22 being contactable with thesecond terminal 24 of the battery cell housing 12. In one aspect of theembodiment, the first terminal pad 18 includes a first pivot point 38about which the first terminal pad 18 is pivotable and the secondterminal pad 22 includes a second pivot point 44 about which the secondterminal pad 22 is pivotable. In one aspect of the embodiment, theovercharge protection device cover assembly 10 further includes a baseplate 16, the base plate 16 defining the reversal device 26, and aspacer plate 54 between the base plate 16 and the first terminal pad 18.In one aspect of the embodiment, the second end portion 36 of the firstterminal pad 18 and the second end portion 42 of the second terminal pad22 are each movable in a direction that is orthogonal to a plant of thebase plate 16.

In one aspect of the embodiment, the reversal device 26 istransitionable between a first configuration and a second configuration.In one aspect of the embodiment, the first terminal pad 18 is a firstdistance from the reversal device 26 when the reversal device 26 is inthe first configuration and the second terminal pad 22 is a seconddistance from the reversal device 26 when the reversal device 26 is inthe first configuration, the first distance being greater than thesecond distance.

In one aspect of the embodiment, each of the first and second terminalpads includes a working thickness T, the working thickness T of thefirst terminal pad and the working thickness T of the second terminalpad being the same.

In one aspect of the embodiment, the first terminal pad 18 includes afirst working thickness T_(FP) and the second terminal pad 22 includes asecond working thickness T_(SP) that is greater than the first workingthickness T_(FP).

In one aspect of the embodiment, transition of the reversal device 26from the first configuration to the second configuration causes theconductive element 28 to contact the second terminal pad 22 before theconductive element 28 contacts the first terminal pad 18.

In one embodiment, an overcharge protection device cover assembly 10includes a base plate 16 including a reversal device 26, the reversaldevice 26 being transitionable between a first configuration and asecond configuration, a first terminal pad 18 having a first lengthL_(FP), a second terminal pad 22 having a second length L_(SP) that isgreater than the first length L_(FP), a conductive element 28 betweenthe reversal device 26 and the first 18 and second 22 terminal pads, anda spacer plate 54 between the base plate 16 and the first terminal pad18. The first terminal pad 18 is a first distance from the base plate 16when the reversal device 26 is in the first configuration and the secondterminal pad 22 is a second distance from the base plate 16 when thereversal device 26 is in the first configuration, the first distancebeing greater than the second distance.

In one aspect of the embodiment, each of the first and second terminalpads includes a working thickness T, the working thickness T of thefirst terminal pad and the working thickness T of the second terminalpad being the same.

In one aspect of the embodiment, the first terminal pad 18 includes afirst working thickness T_(FP) and the second terminal pad 22 includes asecond working thickness Tsp that is greater than the first workingthickness T_(FP).

In one aspect of the embodiment, transition of the reversal device 26from the first configuration to the second configuration causes theconductive element 28 to contact the second terminal pad 22 before theconductive element 28 contacts the first terminal pad 18.

In one embodiment, a battery cell 14 includes a battery cell housing 12,the battery cell housing 12 including first terminal 20 and a secondterminal 24, and an overcharge protection device cover assembly 10affixable to the battery cell housing 12. The overcharge protectiondevice cover assembly 10 includes: a base plate 16 coupled to thebattery cell housing 12 between the first 32 and second 36 terminals,the base plate 16 having a reversal device 26 that is transitionablebetween a first configuration and a second configuration; a firstterminal pad 18 having a first end portion 34, a second end portion 36opposite the first end portion 34, and a first length L_(FP), the firstend portion 34 of the first terminal pad 18 being in contact with thefirst terminal 20; a second terminal pad 22 having a first end portion40, a second end portion 42 opposite the first end portion 40, and asecond length L_(SP) that is greater than the second length L_(FP), thefirst end portion 40 of the second terminal pad 22 being in contact withthe second terminal 24; a conductive element 28 between the reversaldevice 26 and the first 30 and second 34 terminal pads; and a spacerplate 54 between the base plate 16 and the first terminal pad 18. Thefirst terminal pad 18 is a first distance from the base plate 16 whenthe reversal device 26 is in the first configuration and the secondterminal pad 22 is a second distance from the base plate 16 when thereversal device 26 is in the first configuration, the first distancebeing greater than the second distance.

In one aspect of the embodiment, the second end portion of each of thefirst and second terminal pads includes a working thickness T, theworking thickness T of the second end portion of each of the firstterminal pad and the working thickness T of the second terminal padbeing the same.

In one aspect of the embodiment, the second end portion of the firstterminal pad 18 has a first working thickness T_(FP) and the second endportion of the second terminal pad 22 has a second working thicknessT_(SP) that is greater than the first working thickness T_(FP).

In one aspect of the embodiment, transition of the reversal device 26from the first configuration to the second configuration causes theconductive element 28 to contact the second terminal pad 22 before theconductive element 28 contacts the first terminal pad 18.

In one aspect of the embodiment, the conductive element 28 is in contactwith the first 30 and second 34 terminal pads when the conductiveelement 28 is in the second configuration. In one aspect of theembodiment, a short circuit is established in the battery cell 14 whenthe conductive element 28 is in the second configuration.

One or more of the disclosed embodiments, alone or in combination, mayprovide one or more technical effects useful in the manufacture ofbattery cells, and portions of battery cells. The disclosed embodimentsrelate to battery cells that include an overcharge protection assembly.The overcharge protection assembly may include a reversal device that isactivated when a pressure in a casing of the battery cell reaches athreshold value. The activation of the reversal device may causeelectrical contact between terminals of the battery cell, which maycreate an external circuit by electrically coupling the positiveterminal and the negative terminal of the battery cell. Such an externalshort circuit may discharge the battery cell, but the external shortcircuit may prevent thermal runaway and/or permanent damage to thebattery cell. Additionally or alternatively, the short circuit may causea large amount of current to be transmitted through an internal currentcollector of the battery cell, which may cause the current collector tomelt and thereby cut the flow of electric current. It should be notedthat the embodiments described in the specification may have othertechnical effects and can solve other technical problems.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

1. An overcharge protection device cover assembly for use with a batterycell housing, the battery cell housing having a first terminal and asecond terminal, the overcharge protection device cover assemblycomprising: a first terminal pad having a first length, the firstterminal pad being contactable with the first terminal of the batterycell housing; a second terminal pad having a second length that isgreater than the first length, the second terminal pad being contactablewith the second terminal of the battery cell housing; a reversal devicethat is deflectable toward the first and second terminal pads, whereinthe reversal device is transitionable between a first configuration anda second configuration, wherein the first terminal pad is a firstdistance from the reversal device when the reversal device is in thefirst configuration and the second terminal pad is a second distancefrom the reversal device when the reversal device is in the firstconfiguration, and wherein the first distance and the second distanceare different from one another; and a conductive element between thereversal device and the first and second terminal pads.
 2. Theovercharge protection device cover assembly of claim 1, wherein: thefirst terminal pad includes a first end portion and a second end portionopposite the first end portion; the second terminal pad includes a firstend portion and a second end portion opposite the first end portion, thefirst end portion of the first terminal pad being contactable with thefirst terminal of the battery cell housing and the first end portion ofthe second terminal pad being contactable with the second terminal ofthe battery cell housing.
 3. The overcharge protection device coverassembly of claim 2, wherein the first terminal pad includes a firstpivot point about which the first terminal pad is pivotable and thesecond terminal pad includes a second pivot point about which the secondterminal pad is pivotable.
 4. The overcharge protection device coverassembly of claim 3, further comprising: a base plate, the base platedefining the reversal device; and a spacer plate between the base plateand the first terminal pad.
 5. The overcharge protection device coverassembly of claim 4, wherein the second end portion of the firstterminal pad and the second end portion of the second terminal pad areeach movable in a direction that is orthogonal to a plane of the baseplate.
 6. (canceled)
 7. The overcharge protection device cover assemblyof claim 1, wherein the first distance is greater than the seconddistance.
 8. The overcharge protection device cover assembly of claim 7,wherein each of the first and second terminal pads includes a workingthickness, the working thickness of the first terminal pad and theworking thickness of the second terminal pad being the same.
 9. Theovercharge protection device cover assembly of claim 7, wherein thefirst terminal pad includes a first working thickness and the secondterminal pad includes a second working thickness that is greater thanthe first working thickness.
 10. The overcharge protection device coverassembly of claim 7, wherein transition of the reversal device from thefirst configuration to the second configuration causes the conductiveelement to contact the second terminal pad before the conductive elementcontacts the first terminal pad.
 11. An overcharge protection devicecover assembly, the overcharge protection device cover assemblycomprising: a base plate including a reversal device, the reversaldevice being transitionable between a first configuration and a secondconfiguration; a first terminal pad having a first length; a secondterminal pad having a second length that is greater than the firstlength; a conductive element between the reversal device and the firstand second terminal pads; and a spacer plate between the base plate andthe first terminal pad, the first terminal pad being a first distancefrom the base plate when the reversal device is in the firstconfiguration and the second terminal pad being a second distance fromthe base plate when the reversal device is in the first configuration,the first distance being greater than the second distance.
 12. Theovercharge protection device cover assembly of claim 11, wherein each ofthe first and second terminal pads includes a working thickness, theworking thickness of the first terminal pad and the working thickness ofthe second terminal pad being the same.
 13. The overcharge protectiondevice cover assembly of claim 11, wherein the first terminal padincludes a first working thickness and the second terminal pad includesa second working thickness that is greater than the first workingthickness.
 14. The overcharge protection device cover assembly of claim11, wherein transition of the reversal device from the firstconfiguration to the second configuration causes the conductive elementto contact the second terminal pad before the conductive elementcontacts the first terminal pad.
 15. A battery cell comprising: abattery cell housing, the battery cell housing including first terminaland a second terminal; and an overcharge protection device coverassembly affixable to the battery cell housing, the overchargeprotection device cover assembly including: a base plate coupled to thebattery cell housing between the first and second terminals, the baseplate having a reversal device that is transitionable between a firstconfiguration and a second configuration; a first terminal pad having afirst end portion, a second end portion opposite the first end portion,and a first length, the first end portion of the first terminal padbeing in contact with the first terminal; a second terminal pad having afirst end portion, a second end portion opposite the first end portion,and a second length that is greater than the first length, the first endportion of the second terminal pad being in contact with the secondterminal; a conductive element between the reversal device and the firstand second terminal pads; and a spacer plate between the base plate andthe first terminal pad, the first terminal pad being a first distancefrom the base plate when the reversal device is in the firstconfiguration and the second terminal pad being a second distance fromthe base plate when the reversal device is in the first configuration,the first distance being greater than the second distance.
 16. Thebattery cell of claim 15, wherein the second end portion of each of thefirst and second terminal pads includes a working thickness, the workingthickness of the second end portion of the first terminal pad and theworking thickness of the second end portion of the second terminal padbeing the same.
 17. The battery cell of claim 15, wherein the second endportion of the first terminal pad has a first working thickness and thesecond end portion of the second terminal pad has a second workingthickness that is greater than the first working thickness.
 18. Thebattery cell of claim 15, wherein transition of the reversal device fromthe first configuration to the second configuration causes theconductive element to contact the second terminal pad before theconductive element contacts the first terminal pad.
 19. The battery cellof claim 15, wherein the conductive element is in contact with the firstand second terminal pads when the conductive element is in the secondconfiguration.
 20. The battery cell of claim 19, wherein a short circuitis established in the battery cell when the conductive element is in thesecond configuration.